JPH03172738A - Analysis of ni content in ferric chloride solution and system for managing ferric chloride solution - Google Patents

Abstract

PURPOSE:To allow the analysis of an Ni content with high reliability and to allow the exact management of an etching treating liquid by measuring the absorbance of the wavelength region near the absorption peak value of Ni and the absorbance of a wavelength region, the absorbance of which has no relation with the Ni concn. CONSTITUTION:A fresh treating liquid injecting means 2 is attached to a treating tank 1 consisting of a ferric chloride soln. The treating liquid in the treating tank 1 is periodically sampled by a sampling means 3. The absorbance lambda710 to lambda730 of the wavelength region near the absorption peak value of the Ni and the absorbance lambda500 of the wavelength region, the absorbance of which has no relation with the Ni concn. are measured by an absorbance measuring means 4. The absorbance lambda as the concn. of the pure Ni is calculated by a comput ing means 5 from the measured value obtd. in such a manner. The calibration curve of the quantity of the Ni and the absorbance lambda is stored in a calibration curve memory means 6 and the quantity of the Ni corresponding to the calculated absorbance lambda is read out by a reading out means 7. Whether this quantity exceeds a permissible upper limit value or not is judged by a judging means 8. The fresh treating liquid is injected into the treating tank 1 by the means 2 to lower the Ni concn. when the above-mentioned quantity exceeds the permissible value.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for quantitatively analyzing Ni type contained in a ferric chloride solution, and a method for managing a ferric chloride solution using this method. In particular, the present invention relates to a method and system used for liquid management in etching processing during the manufacturing process of photoetching products such as shadow masks for color televisions, printed wiring boards, lead frames, and electrodes for various display tubes.

[Conventional technology]

In recent years, as ICs and LSIs have become more highly integrated, their specifications have tended to become more precise and of higher quality.
Photoetching products such as lead frames and electrodes for various display tubes are also required to be of high quality and precision. Improvements have been made in materials to meet these demands, and in recent years, in particular for shadow mask materials for color TVs, in order to meet the demands for high-definition images, finer hole diameters and hole pitches have been developed to meet the demands for high-definition images. At the same time as the technology advances, improvements are also being made in terms of the heat resistance of the masks themselves. In particular, mask deformation due to thermal expansion of the material due to the electron beam irradiated from the electron gun inside the cathode ray tube has become a problem, and as a countermeasure material, an alloy material (invar material) containing 36% Ni has been developed.
is becoming increasingly used.

Currently, these etching products are generally treated using ferric chloride or cupric chloride, and the liquid management methods vary depending on the material being treated. Usually, Ni
When treating materials that do not contain Fe (99% or more) with ferric chloride, the reaction between ferric chloride and Fe produces non-corrosive ferrous chloride, so chlorine gas (C12), etc. The ferric chloride concentration, which is involved in the processing speed, is regenerated through a reaction caused by the addition of an oxidizing agent, and at the same time, the free acid concentration is also measured and managed.

On the other hand, alloys containing Ni (Invar material, 42
-A11oy, etc.) with ferric chloride, non-corrosive nickel chloride is produced by the reaction between Ni and ferric chloride. Since it is difficult to regenerate nickel chloride into ferric chloride by adding oxidizing agents, etc., as the amount of treatment increases, the proportion of nickel chloride in the total treatment liquid increases, resulting in (1) Decrease in processing speed due to decrease in relative ferric chloride concentration, (2) Adverse effect on material processing surface due to increase in Ni concentration (e.g. unevenness of the processing surface), (3) Release involved in processing reaction rate. This may cause problems such as interference with acid concentration measurement (in ordinary chemical titration methods, the end point is unclear and measurement is difficult), and as a result, product quality will be adversely affected.

Conventional techniques to deal with these problems include calculating the amount of Ni dissolved in advance through theoretical calculations based on the Ni content of the treated material, the number of treatments, the treatment time, etc., and continuously dissolving Ni-free chloride. How to keep the Ni amount below the limit value by replenishing the treatment tank with 2 iron solution or by periodically replacing the solution,
There is a method of continuously analyzing Niff1 using an instrumental analysis method and feeding it back to a system for replenishing new fluid, etc.

In particular, regarding the last method, a system for measuring using spectrophotometry has been devised (Japanese Unexamined Patent Publication No. 6
3-250473, Japanese Patent Application Laid-Open No. 6468483), there is a method of calculating from a calibration curve between the absorbance in the range of 710 to 730 nm using a known Niffi sample and Niff1.

[Problem to be solved by the invention]

In the method using the above spectrophotometric method, in order to clarify the Fe peak and Ni peak in the spectral curve of the ferric chloride solution, addition is made to completely erase the colored absorption band of Fe in iron chloride. 7 depending on the amount of color eraser (phosphoric acid) added.
Because the absorbance in the 10-730 nm region fluctuates,
The value obtained from the calibration curve of Ni amount and absorbance varies. In addition, if the concentration of the ferric chloride solution to be measured changes, the absorbance will change because the mixing ratio with the color erasing agent will change, and the value obtained from the calibration curve of Ni amount and absorbance will similarly change. Put it away.

Due to the above reasons, where the ferric chloride concentration constantly fluctuates, the calibration curve representing the relationship between the amount of Ni and the absorbance cannot be unified, and the reliability of Ni determined from the absorbance becomes low.

Therefore, the object of the present invention is to
Ni in ferric chloride from absorbance in 730 nm region
It is an object of the present invention to provide a highly reliable method for quantitatively analyzing Ni content and a ferric chloride liquid management system using the method by solving the problems of the method of quantitatively analyzing Ni content.

[Means to solve the problem]

In the present invention, in order to solve the problems of the above-mentioned conventional methods, in the absorption photometry method, the wavelength range used for measurement is divided into two.
wavelength range. In the conventional one-wavelength range measurement method, the second chloride
710~ depending on conditions such as iron concentration and color erasing agent dilution rate.
A change occurs in the absorbance in the 730 nm region. This situation is shown in FIG. As is clear from the figure, even if the Ni concentration is constant, 710 to 73
The absorbance in the 0 nm region changes. However, Fe
When a spectral curve is obtained by changing the Ni concentration while keeping the concentration constant, it becomes as shown in FIG. 2, and it can be seen that there is a wavelength range around 500 nm that is not affected by the Ni amount. From this, it can be seen that the absorption at 500 nm in FIG. 1 can be attributed to Fe.

This wavelength range of 500 nm and the amount of Ni contribute to 710~7
By measuring the absorbance in the 30 nm wavelength range and calculating according to the following calculation formula (1), it becomes possible to measure the amount of Ni without being affected by the ferric chloride concentration.

λ=λ710-73°-k・λ,. .・・・・・・・・・
...(1) However, λ: Absorbance as pure Ni concentration. -1,. Absorbance λ in the near 10-730 nm wavelength range. . : Absorbance in the 500 nm wavelength range: Constant As a result of experiments, it has been found that the above constant is approximately 1, and there is no problem even if it is approximated to k=1. Therefore, the above equation (1) can be rewritten as the following equation (2).

λ; λtoo-vao-λ,. .・・・・・・・・・
・・・・・・・・・(2) By the way, during the measurement, the concentration of the phosphoric acid solution used as a color erasing agent for ferric chloride, and
It has been found that by selecting the dilution rate of the sample liquid to be 25% or more and 5 times or less, there is no influence of the ferric chloride concentration or measurement temperature on the measurement accuracy. FIG. 3 shows a graph of the measurement accuracy of the dilution rate.

From this, it can be seen that the lower the dilution rate, the greater the slope and the higher the measurement accuracy. - For boat fishing, in the case of etching treatment liquid, it is desirable to select a dilution rate of 5 times or less. When the dilution rate is selected in this way, F
The masking (color erasure) of e'+ is sufficient, and the second chloride
The influence of iron concentration on absorbance fluctuations is also reduced. In addition, since the dilution rate is relatively low as mentioned above, the absolute amount of phosphoric acid required for color erasing is also large, but if this is small, color erasing will be insufficient, and as mentioned above, the ferric chloride concentration and measurement Since absorbance fluctuations are likely to occur due to temperature, this problem can be solved by increasing the phosphoric acid concentration to the above-mentioned 25% or higher concentration.

By the way, a management system for ferric chloride liquid can be constructed using such a method for analyzing the Ni content in ferric chloride liquid.

Fig. 4 is a block diagram of an example of a configuration for this purpose, in which a new treatment liquid injection means 2 is attached to a treatment tank l using a ferric chloride solution, and the amount of Ni in the treatment [1] is greater than the allowable value. When this occurs, a new processing liquid is injected by the new processing liquid injection means 2 to reduce the Ni concentration therein. The processing liquid in the processing tank 1 is periodically sampled by the processing liquid sampling means 3. The sampled processing liquid has the above-mentioned absorbance λff1o-43° and λ. . By means 4 of measuring the absorbance λ, 1°-1,. and λ
,. .

is measured. From the measured value, λ=λno −43°−
λ$. . The means 5 for calculating calculates the absorbance λ as the pure Ni concentration. On the other hand, this system has Ni
A means 6 for storing a calibration curve between the amount and λ is provided, and a reading means 7 reads out the Ni amount corresponding to λ calculated by the calculation means 5. Judgment means 8 determines whether this amount exceeds the upper limit allowed for processing.
If it exceeds the amount, the required new processing liquid calculating means 9 calculates how much new processing liquid should be added, and the result is sent to the new processing liquid injection means 2. A new treatment liquid is added to the treatment tank 1 in an amount based on the signal.

FIG. 5 is a block diagram of a modification of the configuration shown in FIG. 4, in which the treatment tank 1 using the ferric chloride solution is provided with a treatment liquid exchange means 10 instead of the new treatment liquid injection means 2. 4, the readout means 7 reads out N+th corresponding to λ calculated by the calculation means 5, and the judgment means 8 judges whether this amount exceeds the upper limit allowed for processing. It's the same until you do. Ni by the judgment means 8
When it is determined that the amount is equal to or greater than the allowable upper limit value, the processing liquid in the processing tank I is replaced by the processing liquid exchange means IO.

In both of the examples shown in FIGS. 4 and 5, the processing liquid sampled by the processing liquid sampling means 3 is supplied with a required amount of diluting liquid and color erasing agent by a diluting means and a color erasing side addition means (not shown). is added.

[Effect]

The Ni content in the ferric chloride solution was determined by measuring the absorbance in a wavelength region near the absorption peak value of Ni and the absorbance in a wavelength region where the absorbance is unrelated to the Ni concentration, and quantitatively analyzed the Ni content from both absorbances. Therefore, the error due to the ferric chloride concentration is reduced, and it becomes possible to unify the calibration curve for the Ni content. Therefore, the Ni content can be analyzed with high reliability, and the etching solution can be managed accurately.

〔Example〕

Examples of this invention will be described below.

Using a ferric chloride solution with a specific gravity of 1.470 to 1.530,
A measuring device was installed in the process of processing etching products, and the color erasing agent (phosphoric acid) concentration was set to 28% and the dilution rate was 5 times diluted, and the maximum Ni content was 50 g/j.
! In a state where the concentration fluctuates up to 7.5%, the absorbance against the amount of Ni is λ7. . -7,.

and λsao were measured, and the amount of Ni and λ(=λ, 1°-1,.

−λ,. . ) was calculated. As a result, within the above specific gravity range, it was possible to unify the calibration curves with a verification rate of 99% or more, regardless of the ferric chloride concentration. This calibration curve is shown in FIG. By interlocking with the new processing solution replenishment system shown in FIG. 4, the amount of Ni can always be kept constant, making it possible to manufacture stable etching products.

〔Effect of the invention〕

According to the above-described method for analyzing Ni content in a ferric chloride solution and the ferric chloride solution management system of the present invention, the Ni content in a ferric chloride solution can be measured in a wavelength region near the absorption peak value of Ni. The absorbance of ferric chloride and the absorbance in a wavelength region where the absorbance is not related to the Ni content are measured, and the Ni content is quantitatively analyzed from both absorbances, so the error due to the ferric chloride concentration is reduced,
It became possible to unify the detection line for inclusion 1.

Note that by setting the concentration and dilution rate of the color erasing agent (phosphoric acid) to the above conditions, there is an effect that highly accurate measurement is possible without the influence of the ferric chloride concentration and measurement temperature on the measured value.

Therefore, the Ni content can be analyzed with high reliability, and the etching solution can be managed accurately, making it possible to process etched products of high quality.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the change in absorbance due to a change in Fe concentration when the Ni content is constant, and Figure 2 is a diagram showing the change in absorbance due to a change in Ni content when the Fed content is constant. Figure 3 is a diagram showing the influence of the dilution rate on measurement accuracy, Figure 4 is a block diagram of an example of the configuration of a ferric chloride liquid management system according to the present invention, and Figure 5 is a diagram showing the influence of the dilution rate on measurement accuracy. FIG. 6, a block diagram of the configuration of the modified example, is a diagram showing an actually obtained calibration curve. DESCRIPTION OF SYMBOLS 1... Ferric chloride liquid treatment tank, 2... New processing liquid injection means, 3... Treatment liquid sampling means, 4... Absorbance λ71°130) λsoo measuring means, 5... λ- λI
Q −13°−λ,. . Calculating means, 6...Ni amount and λ
Niff1 corresponding to 7...λ
reading means, 8... means for determining whether NIN is below the processing upper limit value, 9... means for calculating necessary new processing liquid, lO.
・・Processing liquid exchange means Dai Nippon Printing Co., Ltd.

Claims (6)

[Claims] (1) To determine the Ni content in the ferric chloride solution, measure the absorbance in a wavelength region near the absorption peak value of Ni and the absorbance in a wavelength region where the absorbance is not related to the Ni concentration, and calculate the Ni content from both absorbances. A method for analyzing Ni content in a ferric chloride solution, characterized by quantitative analysis. (2) The wavelength region near the absorption peak value of Ni is 710 nm.
2. The method for analyzing Ni content in a ferric chloride solution according to claim 1, wherein absorbance is measured in both of the wavelength ranges, with the wavelength region having no relation to the Ni concentration being 500 nm. (3) The method for analyzing Ni content in a ferric chloride solution according to claim 1 or 2, characterized in that quantitative analysis is performed using the difference between both absorbances. (4) The method according to any one of claims 1 to 3, characterized in that the concentration of the phosphoric acid solution as a color erasing agent is selected to be 25% or more in order to eliminate the influence on the absorbance of Fi. Method for analyzing Ni content in ferric chloride liquid. (5) It has a treatment tank using a ferric chloride solution, and a new treatment liquid injection means is attached to the treatment tank for injecting a new treatment liquid when the Ni concentration in the treatment tank exceeds an allowable value. In the ferric chloride liquid management system, the processing liquid sampling means for sampling the processing liquid in the processing tank, the absorbance in a wavelength region near the Ni absorption peak value of the processing liquid sampled by the processing liquid sampling means means for measuring and absorbance in a wavelength range where the absorbance is unrelated to Ni concentration; means for calculating the difference between the two absorbances measured by the measuring means; and for storing a calibration curve between the amount of Ni contained and the difference between the two absorbances. means for reading out the Ni content corresponding to the difference between both absorbances from the storage means; and means for determining whether the Ni content read out by the reading means exceeds an upper limit allowed for the process. , further comprising means for instructing the new treatment liquid injection means to inject a new treatment liquid when the determination means determines that the amount of Ni contained exceeds the upper limit allowed for the treatment. Ferric chloride liquid management system. (6) A treatment tank with a ferric chloride solution is provided, and a treatment liquid exchange means is attached to the treatment tank for replacing the treatment liquid with a new treatment liquid when the Ni concentration in the treatment tank exceeds an allowable value. In the ferric chloride liquid management system, a processing liquid sampling means for sampling the processing liquid in the processing tank, and N of the processing liquid sampled by the processing liquid sampling means.
means for measuring the absorbance in a wavelength region near the absorption peak value of i and the absorbance in a wavelength region where the absorbance is not related to the Ni concentration;
means for calculating the difference between the two absorbances measured by the measuring means; means for storing a calibration curve between the amount of Ni contained and the difference between the two absorbances; and a means for storing the amount of Ni contained corresponding to the difference between the two absorbances from the storage means. reading means, means for determining whether the amount of Ni contained read by the reading means exceeds the upper limit allowed for processing, and means for determining whether the amount of Ni contained exceeds the upper limit allowed for processing by the judgment means; A ferric chloride liquid management system, comprising means for instructing the processing liquid exchange means to replace the processing liquid with a new processing liquid when it is determined that the processing liquid has changed.